Homology is the observation of one of three types of biological similarities shared among taxa due to sharing a common ancestor. This is in part the scientific explanation backing Charles Darwinβs observations while he was on board the HMS Beagle.
The three types of homologies are broad categories with respects to different aspects of biology: structural, genetic, and developmental homology. Structural homology pertains to the body plan and anatomy of taxa; genetic homology to the chromosomal makeup and molecular sequence of taxa; and developmental homology to the embryonic structure and growth of taxa.